获取最后记录的价值 [英] Get value of Last record

问题描述

我想在SQL Server中创建具有两个字段Sno(int，identity)，Name(Varchar)的表.
表格看起来像

Sno -----文本框1

名称-----文本框2

保存按钮

第一次，文本框1要显示值1.
然后，当我保存记录时，数据要以1,2,3的增量顺序显示.

I want create table with two fields Sno(int,identity),Name(Varchar) in SQL server.
Form Looks Like

Sno -----Text box1

Name-----Text box2

SAVE Button

At first time, text box1 want to display the value 1.
Then when i save the record the data want display increment order 1,2,3......

推荐答案

我不建议创建序数您的代码记录的编号.您可以使用例如身份 [ uniqueidentifier [

I wouldn''t advice to create an ordinal number for your records by your code. You can use for example identity[^].

However, remember that even though the number is auto incremented, you may have gaps for example if a record is deleted and so on. So this number should not used as a meaningful number, just a unique identifier. Another unique identifier mechanism is: uniqueidentifier[^]

Mika的回答非常好！

如果要从表中获取最后一条记录，则有两种方法:
1)使用SELECT TOP(1) AND ORDER BY ... DESC

Mika''s answer is very good!

If you would like to get the last record from your table, there are 2 ways:
1) Using SELECT TOP(1) AND ORDER BY ... DESC

SELECT TOP(1) *
FROM YourTable
ORDER BY FieldID DESC

2)使用表光标 [

2) Using table Cursor[^]

DECLARE a_cursor SCROLL CURSOR FOR
DECLARE @iNum INT
SELECT [FieldID] FROM YourTable
OPEN a_cursor;
-- Fetch the last row in the cursor.
FETCH LAST FROM a_cursor
INTO @iNum;
CLOSE a_cursor;
DEALLOCATE a_cursor

SELECT @iNum

    Dim da As SqlDataAdapter
         Dim i As Integer
da = New SqlDataAdapter("select id from sample order by id desc ", con)
     Dim ds As DataSet = New DataSet()
     da.Fill(ds)
     If ds.Tables(0).Rows.Count > 0 Then
         i = Convert.ToInt32(ds.Tables(0).Rows(0)(0).ToString())
         i = i + 1

         TextBox1.Text = i
     Else

         i = 1
         TextBox1.Text = i
     End If

Then

 Write simple insert quary like
insert into sample values(id,name)

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